Method of reconstructing transcranial images using dual-mode ultrasonics phased array

Abstract

A method of reconstructing transcranial images using a dual-mode ultrasonic phased array includes steps of: controlling channels to emit energy toward an intracranial target point of a patient; respectively generating backscattered radiofrequency (RF) data by using the channels to receive backscattered energy reflected from the intracranial target; and reconstructing an acoustic distribution image based on those backscattered RF data in real-time. Compared with Pre-Treatment Ray Tracing Method, the present invention can display intracranial pressure distribution in real-time; compared with MR Thermometry, the present invention can be applied to low-energy applications without temperature change; and compared with Passive Cavitation Imaging, the present invention can stably present acoustic distribution images without relying on microbubbles.

What is claimed is: 
     
         1 . A method of reconstructing a transcranial image using a dual-mode ultrasonic phased array, applicable to a processing device in signal communication with a plurality of channels forming an array on the dual-mode ultrasonic phased array, the method comprising steps:
 Step (A): controlling the plurality of channels to emit energy to an intracranial target point of a patient;   Step (B): respectively generating backscattered radiofrequency (RF) data by using the plurality of channels to receive backscattered energy reflected from the intracranial target point; and   Step (C): reconstructing an acoustic distribution image in real-time based on the backscattered RF data.   
     
     
         2 . The method according to  claim 1 , wherein before the step of reconstructing the acoustic distribution image, the method further comprises steps:
 acquiring a relative position between the dual-mode ultrasonic phased array and the patient's head; and   calculating phases of the plurality of channels emitting energy to the intracranial target point based on the relative position and a relationship of tissue and acoustics.   
     
     
         3 . The method according to  claim 2 , wherein before the step of calculating the phases of the plurality of channels emitting energy to the intracranial target point, the method further comprises a step:
 calculating a density of intracranial tissue based on Hounsfield Unit (HU) values of a computer tomography corresponding to the patient to acquire the relationship of tissue and acoustics.   
     
     
         4 . The method according to  claim 3 , wherein after the step of calculating the phases of the plurality of channels emitting energy to the intracranial target point, the method further comprises a step: performing phase calibration on the plurality of channels emitting energy according to the relative position of the dual-mode ultrasonic phased array and the patient's head and the relationship of tissue and acoustics.  5 . The method according to  claim 1 , wherein after the step of reconstructing the acoustic distribution image, the method further comprises a step: adjusting energy output by the dual-mode ultrasonic phased array according to the acoustic distribution image. 
     
     
         6 . The method according to claim  5 , wherein the processing device calculates a transcranial decay rate and a compensation parameter according to reflected energy so as to adjust the energy output in real-time. 
     
     
         7 . The method according to  claim 1 , wherein before the step of reconstructing the acoustic distribution image, the method further comprises a step: calculating delay times respectively corresponding to the plurality of channels, the delay times being used to compensate the backscattered RF data. 
     
     
         8 . The method according to  claim 1 , wherein before the step of reconstructing the acoustic distribution image, the method further comprises a step: averaging the backscattered RF data to enhance a quality of the acoustic distribution image. 
     
     
         9 . The method according to  claim 1 , further comprising steps:
 performing Fourier Transform on the backscattered RF data to obtain frequency spectrums; filtering signals of the frequency spectrums to obtain ultra-harmonic signals of frequencies output by the dual-mode ultrasonic phased array; and   reconstructing a cavitation distribution image according to the ultra-harmonic signals.   
     
     
         10 . The method according to  claim 1 , wherein the plurality of channels includes a plurality of first channels and a plurality of second channels; the plurality of first channels is used to perform the step of emitting energy to the intracranial target point; the plurality of second channels is used to perform the step of receiving the backscattered energy. 
     
     
         11 . The method according to  claim 1 , wherein the plurality of channels is configured to perform the step of emitting energy to the intracranial target point and the step of receiving the backscattered energy respectively at different time points. 
     
     
         12 . The method according to  claim 1 , wherein the step of reconstructing the acoustic distribution image in real-time based on the backscattered RF data further includes steps: calculating a reconstructed signal according to the backscattered RF data; and reconstructing the acoustic distribution image, which presents energy distribution, according to the reconstructed signal. 
     
     
         13 . The method according to  claim 12 , wherein the reconstructed signal is obtained according to Equation ( 1 ):
     S ( r   i )=Σ n=1   N   A   ni   ×s   n ( r   ni   , t   i )   (1)
   
       wherein S(r i ) represents the reconstructed signal corresponding to the intracranial target points r i ; A ni  respectively represent a weight coefficient of the nth channel; s n (r ni , t i ) represents the backscattered RF data generated by the nth channel; r ni  respectively represent the distance between the nth channel and the intracranial target point; t i  represents a time interval between a time point at which the nth channel emits energy and a time point at which the nth channel receives the backscattered energy; n is a positive integer. 
     
     
         14 . The method according to  claim 12 , further comprising steps:
 adjusting focuses of the dual-mode ultrasonic phased array, and repeating Step (A) to Step (C) to reconstruct a plurality of acoustic distribution images respectively corresponding to different intracranial target points; and   merging the plurality of acoustic distribution images to obtain a tissue image.   
     
     
         15 . The method according to  claim 12 , further comprising steps:
 integrating an output energy of the dual-mode ultrasonic phased array, an elapsed time after applying energy, and the acoustic distribution image, which presents energy distribution, to work out a temperature increase and a temperature decrease of the intracranial target point; and   reconstructing a temperature distribution image of the intracranial target point according to the temperature increase and the temperature decrease.